Upright vacuum cleaners are well known in the art. Typically, these vacuum cleaners include an upper housing pivotally mounted to a vacuum cleaner foot. The foot is formed with a nozzle opening defined in an underside thereof and may include an agitator mounted therein for loosening dirt and debris from a floor surface. A motor and fan may be mounted to either the foot or the housing for producing suction at the nozzle opening. The suction at the nozzle opening picks up the loosened dirt and debris and produces a flow of dirt-laden air which is ducted to the vacuum cleaner housing.
In conventional vacuum cleaners, the dirt laden air is ducted into a filter bag supported on or within the vacuum cleaner housing. Alternatively, bagless vacuum cleaners duct the flow of dirt-laden air into a dirt separation system having a dirt cup which filters the dirt particles from the airflow before exhausting the filtered airflow into the atmosphere. Various dirt separation systems have been used on bagless vacuum cleaners to separate the dirt particles from the airflow. For example, some vacuum cleaners have dirt cups with outer walls comprising a filter material. Locating the filter material along the outer walls has the distinct advantage of permitting the use of a large amount of filter material similar to the amount of material in a filter bag. However, such vacuum cleaners have a disadvantage of not permitting the operator to view the accumulated material within the dirt cup. Other vacuums, place the filter element in an interior portion of the dirt cup. Such dirt cups do not take advantage of the larger surface available on the outer wall of the dirt cup.
What is needed therefore, is a dirt separation system that overcomes the above-mentioned drawbacks.